Republicans know their repeal votes on Obamacare are symbolic — but repeal remains a potent GOP message on the campaign trail for the 2014 midterm elections.

GOP politicians running for Senate in states like Georgia and Louisiana have been burnishing their Obamacare repeal credentials for months. Some of the Senate candidates are trying to outdo primary opponents in showing how determined they are to roll back the unpopular law. Others hope anti-Obamacare sentiment will let them pick up seats in November that are now held by Democrats, like the one being vacated in Montana by retiring Senate Finance Committee Chairman Max Baucus, who helped write the 2010 health care law.

On Thursday, the House votes for repeal for the first time this year. Members know they can’t knock the law off the books. The Senate is in Democratic hands, and there’s no way President Barack Obama would ever sign a repeal bill. But GOP House members — particularly the freshmen — want to check the “voted to repeal Obamacare” box before they again face voters.

House leaders have not held any repeal votes so far this year, a contrast to the 30-plus votes to repeal the law or pieces of it in the 112th Congress.

But the implausibility of repeal anytime soon hasn’t stopped Republicans from trying to capitalize on the controversy, especially among conservative voters likely to turn out in GOP primaries that will be held early in 2014.

“Let’s make this Obamacare’s last birthday,” says the petition on the campaign website of Montana Senate contender Corey Stapleton, one of two Republicans so far vying to succeed retiring Baucus.

With the health law rolling out in the next few months, the politics could change when people start experiencing benefits that are now abstract. But there’s a lot that can go wrong — from confusion over how to enroll to rising insurance costs that will surely be blamed on the 2010 health law.

Senate Minority Leader Mitch McConnell is looking less likely to have a GOP insurgent challenge in a primary, and he doesn’t even have a first-tier Democratic rival yet. But lately, he’s been sending out a torrent of statements against the health law.

On the Senate floor the other day, he called on the president to “join with Republicans in agreeing to repeal this job-killing law.” A super PAC supporting his reelection, the Kentucky Opportunity Coalition, is underscoring that message. “Tell him, ‘Keep fighting to stop Obamacare in its tracks,’” it said in its first on-air ad.

Rep. Shelley Moore Capito (R-W.Va.), a relative moderate, has a decent shot at flipping the seat of retiring Democratic Sen. Jay Rockefeller into Republican hands. But first, she’s got to push back against any primary challenge from the right. So she, too, is strutting her repeal stuff.

“Along with many in Congress, I voted against the Affordable Care Act in 2009,” she wrote in a recent op-ed in her state’s leading newspaper. “Since then, I have voted on multiple occasions to repeal and defund implementation of the law because Americans deserve better than devastating Medicare cuts, tax increases and mandates.”

Repealing the health care law is a central message in the crowded Georgia GOP primary field in the race for outgoing Republican Sen. Saxby Chambliss’s seat. The group of conservative candidates — notably two House doctors in the race, Reps. Paul Broun and Phil Gingrey — have been repeatedly promising to repeal and replace the law.

“We can repeal it; we must repeal it. Hopefully we’ll have a president three years from now who will sign my Patient Option Act,” Broun said, referring to his own vision for replacing the law.

Similarly, Louisiana Rep. Bill Cassidy, another conservative physician, promised he would “work to replace Obamacare” as he announced his Senate challenge to Sen. Mary Landrieu, a Democrat.

While some candidates are reluctant to admit it would be nearly impossible to repeal the law, even in 2016, others, like Cassidy, talk about trying to dismantle pieces of it or withhold funding. That’s a message the base likes to hear, especially in states where polls show that voters don’t know much about the law.

Public opinion about the law hasn’t changed much since the Supreme Court upheld it last summer, with about half of Americans opposing it and about two in five expressing support, according to an aggregation of polls by Real Clear Politics.

And voters still want lawmakers to keep trying to block or at least change the law rather than accept its existence and move on. Fifty-three percent of respondents to a Kaiser Family Foundation poll in April said opponents should keep trying to change or stop it, while 33 percent said they thought opponents should accept it as the law of the land.

And with numbers like that, it’s no surprise that repeal is campaign fodder — not just in the Senate but in the House races, too. Rep. Randy Hultgren (R-Ill.) said members have to balance the slim chances of repeal in the short term with persistence on an issue that matters to the base. “It just depends on the district how that will play,” Hultgren said. “But it is a constant challenge that we have of serving during our terms but also realizing we’re all up for election every two years.”

As long as public sentiment remains so divided, the “repeal Obamacare” message is unlikely to fade. The prospect for repeal after Obama’s reelection may have declined, but the political environment hasn’t adjusted, said Alan Abramowitz, a political science professor at Emory University, who is watching it unfold in Georgia and elsewhere.

“You might think after the 2012 election, … that would put this to an end,” he said. “But really, the basic dynamics in Washington haven’t changed.”

“I think if you’re worried about a Republican primary, then yeah, it makes a lot of sense,” Abramowitz added. Conservatives tend to turn out for primaries, so any Republican who either has a challenger or is worried about one is going to stress repeal.

Cassidy said he’d be thrilled to be able to repeal the whole law — but that in the meantime, he’d like to dismantle the most objectionable pieces.

He acknowledged that the repeal calls versus the actual odds of repeal may be a bit “confounding,” but he said he’s still pushing to get rid of the law or at least as many pieces of it as he can. “If you say, ‘Wait a second, wouldn’t it be great if we repealed the medical device tax? Wouldn’t it be great if we repealed this provision or that provision?’” it still gets the message across.

At least one fellow Louisiana Republican definitely got the message. Retired Air Force Col. Rob Maness announced this week that he, too, will challenge Landrieu in the 2014 Senate race — which means he’s also taking on Cassidy.

Maness’s reason for jumping in? His announcement said he wants to protect the country from “unconstitutional Big Government schemes like Obamacare.”